140 



DOMESTIC WATER SUPPLIES FOR THE FARM 



of air, but the materials used are as a rule so porous that more or 

 less air gets through them and the well freezes. The use of manure 

 is somewhat more effective, for it warms the air that passes 

 through it, but it involves great danger of pollution. 



Freezing is due to faults in the 

 construction of the well itself and can 

 ordinarily be prevented only by rem- 

 edying the defects of construction. 



In open wells the air obtains ac- 

 cess through the soil at the junction 

 of curb and cover and through cracks 

 in the curb or in the cover. The 

 junction of curb and cover is tight in 

 but few wells, and the cover itself, if 

 of wood, is tight in none. The rem- 

 edy for freezing consists in substitut- 

 ing cement for wood and in tightly 

 fitting it to the curb, which should 

 also be coated with cement for some 

 distance below the surface. 



The conditions in a cased well with 

 escape at bottom are represented in 

 Figure 62, in which A is the outer cas- 

 ing; B, the inner or pump tube; C, 

 the pump cylinder; and D, the well 

 point. When the barometer is high 

 the air is sucked in at E, at the 

 mouth of the well, and passes off into 

 the unsatu rated sand at F. If the 

 well is not pumped, it will not freeze 

 at first, as the pipe contains no water 

 FIG. 62. Conditions governing above the water level G. If the well 



freezing in cased well with escape . , , , i , 



of air at bottom. (Sanford.) ls pumped and the water is raised to 



the cylinder C and up pipe B, the 

 cold air passing between A and B is likely to freeze the well. 



T^lVALVES 



